LAr is widely used as a scintillating medium in particle physics experiments [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}. To facilitate the detection of its VUV scintillation light (peaked at 128 [10]}), the wavelength shifter TPB is often used [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}. TPB absorbs the short-wavelength light and re-emits it in a region between 380 and 600, as shown in shiftingspectra (top).
The emission in this spectral region is of advantage: it matches well the quantum efficiency of commercial photodetectors, which often peak in the violet to blue spectral region [5]}, [20]}, the efficiency of reflectors, as it will be shown in this work, and the absorption of light guiding fibers, such as those used in LEGEND-200, shown in shiftingspectra (bottom).
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